The long term goal of this research is to prepare mammalian rDNA and rDNA chromatin in large quantities, to achieve accurate in vitro transcription and to understand possible levels of transcriptional control. Specifically, we propose to: I. Isolate mouse ribosomal RNA genes (rDNA) by techniques already established in our laboratory: A. Insert the two Eco R-1 fragments of this rDNA into a plasmid; B. Characterize these isolated genes by a detailed restriction nuclease map; C. Characterize the 5' oligonucleotide of the primary 45S transcript; D. Characterize these isolated genes by electron microscopy; E. Isolate specific promoters of rDNA genes. II. Chrotatin: isolation, reconstitution and transcription: A. Determine transcriptional specificity; B. Isolate nucleolar chromatin; C. Isolate specific rDNA chromatin; D. Reconstitute rDNA and nucleolar chromosomal proteins; E. Transcribe rDNA chromatin, reconstituted chromatin and rDNA with homologous RNA polymerase I and assay specificity of transcription.